Last week I wrote about the challenges of the current Ebola virus outbreak, talking about some details linked to the virus itself, and also some challenges that mean this outbreak may be more challenging to manage. I was involved in previous outbreaks, but definitely in a peripheral support capacity, because of my underlying autoimmune condition I did not travel to Sierra Leone. Context and learning from previous events is important however, so I tapped my good friend and colleague Ant De Souza, who was directly involved in supporting diagnostics, to write me a guest blog of his experiences.
Anthony De Souza is an award-winning Healthcare Science educator with over a decade of experience as Biomedical Scientist in microbiology. He was the first Healthcare Scientist to gain a permanent Practice Educator post, a post he has only continued to develop and expand since its inception. Ant’s transition into strategic education leadership has empowered the Healthcare Science workforce to improve patient outcomes based on his approach; which links strengthening multidisciplinary collaboration, expanding clinical capabilities, and elevating the profile of the healthcare science workforce to ensure they are invited to have a seat at the table. The impact of this has been recognised not just by me, but by him being named on The Pathologist’s Power List for his outstanding contributions to the field.
Ebola Deployment, Sierra Leone – A Personal Reflection
In 2015, when an urgent appeal was issued by Public Health England (now UKHSA) for scientists to support the Ebola crisis in West Africa, I didn’t hesitate—I knew I had to go.
In the past, I’d seen similar calls for volunteers and questioned whether my skills were enough to make a meaningful contribution. The last thing I would ever want was to become a burden on a mission of such importance. But this time felt different. For the first time, my experience, confidence, and mindset aligned with what was needed. I was working as a Band 6 Biomedical Scientist at Watford General Hospital, in a busy microbiology department delivering a 24/7 service. I was used to working under pressure, and I felt ready to contribute.
Before committing, I spoke with my colleagues. A five-week deployment would mean they would take on additional workload, and it was important to me that I had their full support. With their encouragement, I signed up.
Preparation and training
Preparation for deployment was thorough and, at times, intense. I travelled to Porton Down in Salisbury for specialist training, where we learned how to work safely with high-risk pathogens such as Ebola. This included simulation exercises in a laboratory environment designed to mirror the Kerrytown facility, where we practised managing realistic scenarios, including equipment failures and power outages.
We also completed security awareness and hostage survival training, alongside a series of vaccinations for diseases such as yellow fever, cholera, and typhoid. Anti-malarial medication was essential. The preparation highlighted not only the scientific challenges ahead, but also the environmental and personal risks we would face.
The journey
Getting to Sierra Leone was a journey in itself. We travelled by plane, transferred in Morocco, then boarded another flight to Freetown. From there, the journey continued by minibus to a port, a boat crossing, and finally another minibus to the site.
It was a strange experience travelling with a group of people I had never met—yet over the course of five weeks, these individuals would become a close-knit team.
Arrival and first impressions
On arrival, small behavioural changes immediately became part of daily life. Handshakes were replaced with elbow taps, a simple but important measure to reduce transmission risk. Regular temperature checks became routine, particularly at checkpoints when travelling to and from the treatment centre.
We were based at the Ebola Treatment Centre (ETC) in Kerrytown, outside of Freetown—a facility built by the British Army Royal Engineers and funded by the Department for International Development. The scale of the operation was impressive, and there was a strong sense of shared purpose. People from different organisations and backgrounds worked together with a single goal.
The ETC was divided into zones based on risk, from green (low-risk areas) to red (high-risk patient areas). Full personal protective equipment (PPE) was mandatory in higher-risk areas.
Working in the laboratory
Our laboratory was located centrally within the site, shared with the Ministry of Defence. After donning PPE, we met the outgoing team and received a rapid but essential handover. For a few days, we worked alongside them before taking full responsibility.
Our role was to test blood and swab samples from individuals suspected of having Ebola. We operated six days a week, with two teams of six covering shifts from 06:00 to 22:00.
Many samples came from community settings, including remote villages. A significant proportion were post-mortem samples, taken to determine whether Ebola had caused the death. The high number of samples from children and infants was particularly difficult to process emotionally.
Specimen reception took place outside the lab. Samples were placed into chlorine solution for decontamination before being handled further. Wearing full PPE in the heat of the sun was physically exhausting, and the need for constant vigilance—checking for incorrectly packaged samples or hidden sharps—added to the pressure.
Inside the lab, resources were basic but functional. The space had sealed cement benches, limited air conditioning, and no negative pressure system. Testing was carried out using PCR techniques for Ebola, alongside POCT testing for malaria. A flexible film isolator was used to safely inactivate the virus before analysis.
Life beyond the lab
Outside of the laboratory, the scale of the public health response was visible everywhere. Posters, radio messages, and community outreach efforts aimed to educate people about Ebola transmission, safe burial practices, and how to protect themselves.
Strict measures were in place:
Large gatherings were prohibited
Schools and religious services were disrupted
Curfews were enforced
Checkpoints monitored movement and health status
Movement restrictions between districts
Daily life, as it once was, had largely come to a standstill.
Cultural challenges and adaptation
One of the most striking aspects of the outbreak was its impact on traditional burial practices.
In Sierra Leone, burial rituals are deeply rooted in cultural and religious beliefs. Traditionally, families wash, dress, and physically say goodbye to loved ones. However, in the context of Ebola, these practices posed a significant risk, as the virus remains highly infectious after death.
To reduce transmission, specially trained burial teams were introduced. These teams worked closely with communities and religious leaders to adapt traditions safely. While physical contact was removed, efforts were made to preserve dignity—allowing families to view the body from a distance, limiting attendees, and involving community leaders in the process.
This collaboration was essential. Without it, there was a real risk that families would carry out burials in secret, increasing the spread of the virus.
Reflections
There is much I could say about my time in Sierra Leone—far more than can fit into a single blog. The work was challenging, both physically and emotionally. There were moments of exhaustion, uncertainty, and sadness.
But above all, what stays with me is the resilience of the people.
In the face of immense hardship, communities adapted their traditions, supported one another, and worked alongside international teams to combat the outbreak. It was a powerful reminder that effective public health is not just about science or medicine—it is about trust, collaboration, and cultural understanding.
This experience reshaped my perspective on global health, teamwork, and the role we each play in times of crisis. It remains one of the most challenging and meaningful periods of my career.
Infectious diseases have been in the news a lot over the last few months, between Hantavirus, Listeria and raw milk, and even Screwworm in cattle, it is hard to ignore the headlines, and after the pandemic it feels like every news article declares a risk to all human life. Ebola is, however, an incredibly difficult virus to manage, with devastating consequences for both countries and communities and so despite the instinct to hide from the reporting we need to continue to engage with the information that is coming out.
From an infection point alone this outbreak is worth discussing, but it is especially pertinent because aside from the impact it has locally, is the fact that the number of people currently dying and infected has likely been directly impacted by global policy choices linked to de-funding United States Agency for International Development (USAID). Combine this with the US decision to pull out of the World Health Organisation (WHO) reducing funding for international health responses, has resulted in a public health emergency that took longer to detect, and now requires managing with both less resources, and less available expertise of previous pandemics. All of which lead to making an already difficult and dangerous situation considerably more challenging.
We live in a global community, and the idea that you can step away from global responsibilities without consequence is more than delusional, it is dangerous, so ‘sorry, not sorry’ for the politics in this one, I think it’s too important to ignore.
Previous outbreaks
There have been a number of Ebola outbreaks since the Ebola virus was first identified in 1976. The initial outbreak included two near-simultaneous outbreaks in Central Africa: one in Yambuku, Zaire (now the Democratic Republic of the Congo), near the Ebola River, and the other in Nzara, Sudan (now South Sudan). The largest outbreak, and the one many of us will remember due to both the substantial media coverage and global health response, occurred in and around Sierra Leone. This 2014–2016 outbreak had more than 28,600 cases reported.
The Centres for Disease Control (CDC) figure show these outbreaks, and the causative Ebola virus (see Ebola virus section below for more details on viral species).
The key takeaway is that the virus causing this outbreak, the Bundibugyo virus, is a rare cause of Ebola virus outbreaks, with considerably less know and understood about how the virus is transmitted, and how it can be detected and managed. This leads to an even greater need for a rapid global response, both in terms of public health, but also in terms of research focus. Making the delay in both even more impactful, and the need for us to get on top of it even more urgent. Some of our prior learning can be ported, but so much of it cannot.
On the 17th May the WHO declared the current scenario in the Democratic Republic of the Congo (DRC) and Uganda a public health emergency of international concern, but what does this mean? Well, the WHO defines it as of an extraordinary, sudden, or unexpected public health event with a risk to other countries through the international spread of disease, potentially requiring a coordinated global response.
On the 5th June the African Centres for Disease Control and WHO launched a joint Ebola continent preparedness and response plan of $518 million to support African countries to prepare for, rapidly detect, and respond to the outbreak.
Ebola virus has a number of different variants, and the current outbreak is caused by the Bundibungyo virus. As of the 6th June there have been 515 confirmed cases, with 91 deaths (17.7%). Uganda has 19 confirmed cases and 2 deaths (10.5%). It is worth considering that these numbers are likely to be a significant under estimate, as laboratory backlogs, plus some level of distrust in healthcare systems, are likely to lead to a reduction in confirmed cases, but I’ll discuss the difference between confirmed, probably, and possible cases later. At the moment, all onward cases are still linked with travel to DRC, but patients are currently being treated or followed up in a number of countries outside of Africa, including in Brazil, Germany, and Italy.
Well, the first thing to realise is that it is not a single virus. Ebola viruses are part of the filoviridae family, most commonly referred to as Filoviruses. They are zoonotic pathogens (associated with animals) that survive in what are known as reservoir species. These are non-human reservoirs, possibly bats, where the virus can circulate without harming the host and leads to occasional spillover into humans where disease is then detected. Ebola disease (EBOD) is a rare and often severe illness in humans that is frequently fatal.
Ebola disease is caused by a group of viruses that belong to the Orthoebolavirus genus of the filoviridae family. Six species of Orthoebolaviruses have been identified to date,with 4 causing disease in humans, three of which are known to cause large outbreaks: Zaire Ebola virus, Sudan virus and Bundibugyo virus. The zoonotic reservoirs are not well understood for Ebola viruses, unlike those for Marburg viruses where a host reservoir has been established by direct isolation from bats.
NB Marburg disease (MARD) caused by Marburg virus was the first filovirus to be discovered in 1967 and also causes disease in humans, but is not an Ebola virus. Ebola Reston virus (RESTV), is another Ebola virus that has been detected in humans but appears to infect them sub-clinically i.e. with no symptoms, and so transmission routes and impacts are not well understood. It does however cause EBOD disease in non-human primates and has been detected in animals such as pigs in the Philippines and China, so there may be a zoonotic reservoir for this virus similar to other members of the genus. This is the virus that featured in The Hot Zone book by Robert Preston, based on the New Yorker article Crisis in the Hot Zone (1992).
Filoviruses are enveloped, non-segmented, negative-sense RNA viruses. The genomes between Bundibugyo and Zaire Ebola species differ by about 30%, and the pathogenesis and clinical outcomes also appear to differ, but there is still limited information regarding the viral mechanism/s that lead to these differences. Importantly, it is worth noting that the cause of the current outbreak, Bundibugyo Ebolavirus, behaves differently in terms of mortality than the more commonly detected outbreak species. Vaccines and other targeted therapy are also not yet established, as the virus has been seen much less frequently.
What are the symptoms?
Patients usually have an initial non-specific presentation which includes fever with malaise (discomfort/unease), fatigue, and myalgia (muscle pain). A few days after this, patients may develop gastrointestinal infections that can include anorexia (loss of appetite), nausea, vomiting, and diarrhoea. Although many people associate EBOD with haemorrhagic fever (i.e. temperatures and bleeding), bleeding abnormalities actually occur in less than half of patients. If bleeding is present, it is usually linked to bleeding from the gums, subconjunctival haemorrhage (broken blood vessels in the eye), and blood in vomit and stool.
The incubation period is between 2 to 21 days (typically, 6 to 10 days) and probably depends on the Ebola virus, as well as the exposure dose and route.
Diagnosis and patient management
Diagnostic testing for Ebola is mainly via reverse transcription–polymerase chain reaction (RT-PCR) targeting the RNA of the virus, but it is made more challenging because it can only be detected in blood once symptoms appear. It is also possible to use Antigen-Capture Enzyme-Linked Immunosorbent Assay (ELISA) tests, these are often less sensitive but easier to implement. Point of care tests, finger prick tests, can also be used but they again have much lower sensitivity than PCR. Many of these tests have been designed for the main outbreak strains of Ebola, and so modification may be needed to allow detection of the Bundibugyo virus, or test sensitivity may be further reduced.
Once patients have developed symptoms, especially during this outbreak as there is a lack of specific treatment options, the main response is linked to supportive care:
Fluid & electrolyte resuscitation as patients have severe fluid loss from diarrhoea and vomiting
Cardiovascular support as patients frequently go into shock
Respiratory support, as patients enter respiratory failure, using equipment such as ventilators
Symptom management as patients may end up needing dialysis for renal failure
Most of which require complex medical equipment which may not be available, or available in large enough numbers within local treatment centres. Lack of equipment availability and access to supportive treatments directly impacts clinical outcomes. The mortality (death) rates without treatment also show a great disparity between Ebola viruses:
Ebola Zaire: 90% (20 – 40% with early treatment and supportive therapy intervention)
Sudan virus: 50% (no approved vaccines or specific antiviral therapeutics available)
Bundibugyo virus: 30% (no approved vaccines or specific antiviral therapeutics available)
Although there isn’t currently an established treatment for Bundibugyo virus, Peter Stafford, the US doctor who contracted Ebola in DRC and was flown to Germany, has been treated with an experimental antibody MBP-134. The BBC has also reported that three vaccines are currently in development which would target the glycoprotein of the Bundibugyo Ebola virus.
Each vaccine aims to train the body to spot the same structure on the surface of the virus but each uses a different technology in order to support an immune response. All three still require testing using clinical trials, and so although it is good that vaccines are being developed, their ability to influence the outbreak is currently still unknown.
For patients that recover, post infection morbidity (long term effects) have not always been well captured due to the devastating impacts of the outbreaks themselves, but during the 2014–2016 EBOV epidemic caused by Ebola Zaire, musculoskeletal pain, headache, encephalitis, and ocular problems were noted in survivors and were referred to collectively as the “post-Ebola syndrome.” Recovery, therefore, can be a protracted process and is likely to vary by causative species.
One challenge for outbreaks on this scale, and for Ebola viruses in particular, is the fact that cases occur throughout communities as well as in healthcare settings. Some of the people most needed to stop spread and to care for patients are the ones at the highest risk of acquisition. Those caring for the living, and the dead, as well as those who are going into homes and other environments to make them safe again for others. The level of selflessness required is huge, especially when you are having to step up knowing that the equipment and support you need to keep you safe may not be there.
During this outbreak there have been numerous reports of people putting themselves at risk to do their roles as items like personal protective equipment (PPE) are just not available. This happens because, although Ebola is spread by close contact with blood and bodily fluids, those infected produce significant amounts of excretions that are also likely to be heavily viral loaded. I talked in the patient management section that one of the biggest challenges is fluid loss via diarrhoea and vomiting and all of those fluids contain risk for those caring for them, or their environment.
Some of the additional challenges that occur during Ebola outbreaks are linked to how it impacts communities. Traditional burial practices often require kissing or interacting with the dead. In many Congolese communities, physical contact with the body is seen as a vital, respectful “final farewell”. This isn’t just a ‘nice to have’ it’s part of embedded in ritual and is highly significant as a way of saying goodbye to loved ones. There are also components that include family members washing the deceased. This is obviously a significant risk moment for transmission.
During significant outbreaks bodies may be disposed of using safe and dignified burial protocols, meaning funerals are undertaken using no touch protocols (the family cannot see or touch the body), bodies are sealed and specially transported, and bodies are buried in deep graves of at least 2 meters deep. Funerals themselves are events where people gather, which may be impacted public heath regulations, so at a time where people are most vulnerable they may expected to manage without support of friends and family, or the rituals traditionally used to help process loss. This can cause to distrust of authority and can lead to clashes between communities and those enforcing the protocols.
On final thing to consider for filovirus spread is that they have been detected in multiple body fluids, including breast milk and semen, in survivors of infection. The persistence in semen, with the potential for sexual transmission has been noted for more than 500 days after disease onset, amd is a serious concern for recovering individuals. However, onward transmission this long after disease onset is very rare with undetermined effects. Even so, this means that survivors and communities may need to consider transmission for protracted periods post recovery and it can represent a source of anxiety.
How is it managed differently?
Ebola is classified as a Risk Group 4 (or Biosafety Level 4, BSL-4) pathogen, meaning that is requires the highest level of biological containment This impacts everything from the way patients are diagnosed and managed in clinical environments, to what kind of laboratory facilities are required to work in developing vaccines and other treatments.
Within the UK it is referred to as a high consequence infectious disease (HCID) which is defined based on the following criteria:
Requires an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely
Acute infectious disease
Typically has a high case-fatality rate
May not have effective prophylaxis or treatment
Often difficult to recognise and detect rapidly
Ability to spread in the community and within healthcare settings
Local guidelines for those managing these kinds of outbreaks evolved a lot as a results of the 2014 – 2016 Ebola Zaire outbreak, where the CDC modified guidance, in part due to the number of healthcare worker acquisitions early in the process.
As it is not just those in hospitals that require PPE to protect staff, the WHO have also released guidance to aid decision making about what kind of PPE is needed for different workers and interactions across the patient pathway. This obviously has a caveat that if the PPE is not available you are not able to wear it.
Key infection prevention and control measures in the World Health Organization (WHO) guideline for Ebola Willet V et al. BMJ 2024; 384 :p2811
There are also some fantastic design solutions that can enable patients to be cared for in a way that limits the exposure of those undertaking that caring. These solutions also support patients having continued access for families, where they can be seen and communicate. This is also important as families may be expected to continue to provide food, even during hospitalisation, meaning they need to ve able to visit safely.
From the videos that I have seen, these facilities do not seem to be widely accessibly within the DRC, but the scenario might quickly change with the increasing recognition of the need for a global response to the outbreak.
Although it would be nice to imagine that everyone is being cared for in facilities, like those pictured above, many of the reports I have seen are much more similar to the New York Times video pictured below, which is really night and day to what we would wish for patients, staff, and families in terms of infrastructure access.
The world cup has just started. People are travelling from all over the world to the USA, Canada, and Mexico. The report below shows some of the challenges that this kind of travel can lead to.
Events like these have led to places like the European Centres for Disease Control (ECDC) to issue guidance on what to think about if a passenger develops symptoms on a flight. This is so crucial because, as discussed, the initial symptoms are pretty non-specific, and if someone has a possible contact history it can be difficult to separate EBOD from a number of other infections that could initially present the same way.
They have also issues guidance about who might need to be followed up after an exposure event. Anxiety can drive extreme responses to having a probable/confirmed case, and so having guidance in these circumstances is key. As Ebola is transmitted by direct contact it is important to be able to differentiate those who are contacts from others who will have just been in the same space but are not at minimal to no risk (contact free exposure has a risk if <1%).
Terminology is key
As I’ve been talking about possible/probably/confirmed cases I thought it was important to include what those definitions actually mean within the UK health setting at least:
Confirmed case
An individual (alive or dead) with a positive laboratory test result (real time polymerase chain reaction (PCR)) from a blood or other body fluid sample.
Probable case
An individual for whom no laboratory results are available (for example waiting for testing or results), who meets both of the following criteria:
Clinical illness compatible with EBOD including any of the following symptoms:
fever (temperature greater than 37.5°C)
severe weakness
severe headache
myalgia
abdominal pain
sore throat
vomiting
diarrhoea
unexplained haemorrhage
PLUS
Contact with an Ebola virus in one or more of the following ways in the 21 days before the onset of symptoms:
contact with an identified potential source of EBOD (for example, direct contact with a probable or confirmed case without wearing adequate PPE or where there were breaches in PPE
exposure to an Ebola virus-infected body fluids or tissues without wearing adequate PPE or where there were breaches in PPE
direct handling of bats, antelopes or primates, from Ebola affected areas without wearing adequate PPE or where there were breaches in PPE
Possible case
A possible case is a deceased individual with epidemiological risks for EBOD
OR
An individual for whom no laboratory results are available (for example waiting for testing or results), but who meets both of the following criteria:
Clinical illness compatible with EBOD including any of the following symptoms:
fever (temperature greater than 37.5°C)
severe weakness
severe headache
myalgia
abdominal pain
sore throat
vomiting
diarrhoea
unexplained haemorrhage
PLUS
One or more of the following epidemiological criteria in the 21 days before the onset of symptoms:
history of travel to EBOD affected areas
direct contact with a confirmed case of EBOD,
or their body fluids (including laboratory staff), but trained and wore appropriate PPE, and had no known breaches in PPE
direct contact with a confirmed case of EBOD, or their body fluids (including laboratory staff), but trained and wore appropriate PPE, and had no known breaches in PPE
For someone arriving into the NHS, the application of these terms in linked to the flow chart below (https://www.gov.uk/government/collections/ebola-virus-disease-clinical-management-and-guidance) with the guidance last updated 4 September 2025. This also helps to remind people to go through steps such as ruling out other possible causes for the symptoms present, such as malaria.
Being able to use precise case definitions means that healthcare staff can ensure that the level of PPE and other protections are matched to the likelihood of risk being present.
As discussed at the start of this post, returning travelers or healthcare workers are already being monitored in numerous countries outside of the outbreak zones, and this is only likely to increase within the next 21 days, linked to the incubation period of the virus.
Until the infrastructure is present to support prevention of onward transmission the risk of global spread will continue to be present. Let me be honest here, I don’t think this is turning into a pandemic. I think there may be risk of acquisition to a small number of healthcare workers if for any reason communication linked to prior travel history fails. This isn’t the point though. We should not just mount public health responses because of a fear that they may impact us personally. I think we have an obligation to utilise the knowledge, experience, and resources available to help save, potentially, thousands of lives.
The time of it taking months of sea travel to get from point A to point B are far behind us. You can be anywhere in the globe in 24 hours, far shorter than the shortest incubation period for most infectious diseases. If the COVID-19 pandemic taught those of us working in the world of infection anything it was that global networks can make a real difference. A difference is the time it takes to recognise that there is a problem to be addressed. A difference in the number of people who are impacted. A difference in the time it takes to take a possible solution to an infectious problem, like vaccines, to a state where they are ready to be implemented.
We cannot live in a world where we think in terms of them and us. Where we think something isn’t happening in our back yard and therefore we don’t need to get involved. The truth is so far from this. Global health has the word global in it for a reason, and the eco systems we live in are global. We need to make networks and connections stronger, not let them be degraded.
So let’s put the pressure on where we can, use what influence we have, and try to ensure that the outcome of this outbreak is not determined by what resources are lacking and who makes the expertise available to help. Let’s behave as we hope someone else would in return, step up and be counted in order to save lives. Let’s be the global family that the pandemic showed us we could be if we tried.
Content warning – this one is long, and is heavier on the detail than usual. It kind of needed to be as people have died. However, if you want the Cliff Notes version, no, there is no need to panic as Hantavirus is not going to be the cause of the next pandemic.
Everyone seems to be talking about Hantavirus right now, well they were, now people are also talking about Ebola and meningitis. It does rather feel like the infectious disease of the week right now. Despite a lot of effort by scientists and healthcare professionals there seems to be an appetite for panic linked to this. It is worth knowing that although Hantavirus is considered to be a high consequence infectious disease (HCID), that is mainly because it is linked to a potentially severe outcome for an individual if infection is confirmed, rather than potential for wide scale spread.
As I’m being asked about this by everyone from cab drivers to healthcare professionals, and faced with panicked social media commentary about whether this is going to be another pandemic, I thought I should share some of the information that is out there in order to support the ‘don’t panic’ key messaging. I think it is important to note, however, that I am not a Hantavirus expert, just your standard infection prevention and control professional, but having studied zoology in a previous life I couldn’t miss the opportunity to talk about a zoonotic (linked to spread from animals) infection.
What is the current scenario?
The cruise ship (MV Hondius) that is making headlines departed from Ushuaia, Argentina, on April 1, 2026, and traveled across the South Atlantic Ocean, stopping at several remote locations that including excursions and the opportunity for passengers to get off the ship, standard cruise fare but with more unusual destinations. These included Antarctica, South Georgia Island, Tristan da Cunha, Saint Helena, and Ascension Island.
The ship itself carried 147 people (86 passengers and 61 crew) from 23 different countries, so small for a cruise but still a sizable mix of people to have in one space.
The extent of their contact with wildlife before or during the expedition is either unknown or disputed, although there are plenty of rumours linked to bird watching etc. The importance of all of which will become apparent when we talk more about the virus and it’s standard transmission routes.
It is also worth noting, that unlike many cruises which have a curcular route with all passengers embarking and disembarking at the same point, with this cruise a number of passengers departed at various points as part of planned departures, therefore dissemination of some people involved had already occurred before any clinical symptoms were understood.
Headlines began to appear linked to a possible outbreak onboard in early May, with the outbreak developing, and more information gradually becoming available, as so often happens during any outbreak situation.
What are Hantaviruses?
First let’s start with the fact that Hantaviruses are very different from the viruses that we have seen causing pandemics over the last century. Although all three are RNA viruses, Hantaviruses are different in structure, transmission and disease presentation to both coronaviruses and influenza viruses. They demonstrates low comparative rates of mutation and very limited person to person spread, so the same epidemiological principles do not apply.
Hantaviruses are RNA viruses that are part of the genus Orthohantavirus. They were named after the Hanta river in South Korea in 1978 (originally called the Hantaan virus) and consist of a family of viruses rather than one single disease, with over 20 species known. As a viral group they have since been split into Old World Hantaviruses and New World Hantaviruses, with viruses found to circulate not just within rodents but also within moles, shrews and other animals. They circulate asymptomatically within their natural zoonotic reservoirs without causing symptomatic infection. When humans are exposed, and infection caused, it is typically due to spread from their normal reservoir with exposure due to interaction with bodily fluids, such as dried urine and droppings.
Different Hantavirus species are associated with different animal reservoirs and their associated geographical territories, as well as leading to different clinical presentations in human infection. Old World Hantaviruses are linked with hemorrhagic fever with renal syndrome (HFRS) and are geographically associated with Africa, Asia, and Europe. New World Hantaviruses are associated with hantavirus cardiopulmonary syndrome (HCPS) have a geographical and have a distribution across the Americas, sometimes also called hantavirus pulmonary syndrome (HPS). As the cruise exposure focus is mostly linked to South America, due to both cruise stops and clinical HCPS presentation, the main animal reservoirs of interest are:
Long-tailed Pygmy Rice Rat (Oligoryzomys longicaudatus)
Pygmy Rice Rats (Oligoryzomys species)
Vesper Mice (Calomys species)
Although there have been a number of cases in the current cluster confirmed as positive for the Andes virus, for context, in Europe (according to ECDC), just under 1,900 cases were recorded in 2023 across all different strains/species of Hantavirus. In the Americas, 8 countries reported 229 cases in 2025. There are, therefore, cases of Hantavirus infection detected annually across the globe, and although not huge numbers the impacts on individuals can be significant. The number of cases that are currently being observed linked to the cruise are therefore considered to be an outbreak, but the risk is mainly due to how individuals that will need to be repatriated to their native countries will be managed and how to ensure the best possible outcomes for those exposed.
What are Zoonotic infections?
A zoonosis (or zoonotic infection) is an infectious disease that can jump from a non-human animal to humans. Traditionally it will have no, or limited, ongoing human to human spread. Transmission can be:
Direct – touching, petting, biting, leading to direct contamination by saliva, blood, urine, or other bodily fluids
Indirect – exposure to saliva, blood, urine, or other bodily fluids via indirect routes such as contamination linked to food, contaminated environments where animal reservoirs live (soil, water etc), contaminated objects
Vector borne – not linked to Hantaviruses, but for other organisms can be spread linked to insect carriage and transmission via insect bites
I’ve talked about the fact that Hantaviruses have animal reservoirs. But which animal, depends on the Hantavirus species, which then impacts where there is a risk of acquisition, as you can’t be exposed if the animal doesn’t live there.
The cruise had been visiting remote wildlife areas, so a passenger could have come into contact with the virus then, or before boarding the ship, as the incubation period is prolongued. This can make contact tracing and understanding the epidemiology more challenging, at least initially, and it is possible that the initial transmission event will never be well understood. The animal reservoir associated with the identified Andes virus, the causative agent of the outbreak, long-tailed pygmy rice rat (Oligoryzomys longicaudatus) and Pygmy Rice Rats (Oligoryzomys species) which can help to pin down broad areas, but not precise transmission route.
Transmission
Transmission linked to zoonotic infection happens in two main ways, transmission within the animal reservoir where infection is usually without any symptoms (asymptomatic), and exposure to humans to the virus circulating within the animal reservoir.
Within the animal reservoir transmission can be linked to moments like aggressive acts, such as biting and scratching where saliva or bodily fluids may be transferred. This is probably one of the primary mechanisms. Animals may also share environments leading to close contact, such as sharing nests, and viral transmission can be linked to exposure in close quarters.
This transmission linked to close contact is also an unusual feature of the Andes Hantavirus and can occur in humans and not just within the animal reservoir. Even so, human to human transmission is relatively rare, but can occur when individuals have prolongued close contact with someone who is symptomatic, especially if exchange of bodily fluids can occur via kissing or other close contact. There is also believed to be an airborne transmission route for the Andes virus, although the route by which this occurs is not well understood. This is addition to the transmission routes from the animal reservoirs that can be due to a number of exposure routes:
The initial clinical presentation of the 70-year-old Dutch passenger, who developed a fever, headache, and diarrhea day 6 of the cruise, five full days after boarding, and who then died on day 11. This timeline means the passenger is unlikely to have acquired Hantavirus onboard as the minimum Hantavirus incubation is believed to be 7 days, meaning that the exposure was likely to have occurred before the passengers even boarded the ship. Ongoing transmission onboard is therefore unlikely to have been point source from an animal exposure, and is more likely to have been linked to close contact of human passengers.
Clinical presentation
Initial presentation of HCPS is pretty generic, and could easily be hard to recognise as Hantavirus infection without a string travel or exposure history. The prodrome phase, or early onset phase is usually 1 – 5 days long and can occur 4-42 days after exposure. Symptoms can be confused with many other viral illnesses and include:
High fever, chills, and profound fatigue
Severe myalgia (muscle aches), particularly in large muscle groups like the thighs and back
Prominent gastrointestinal symptoms: nausea, vomiting, diarrhea, and abdominal pain
Headaches and dizziness
One to two days after the initial phase patients can enter a cardiopulmonary phase where patients can become critically unwell:
Rapidly progressive dyspnea (shortness of breath) and hypoxia
Noncardiogenic pulmonary edema (fluid in the lungs) and coughing
Hypotension, tachycardia, and cardiogenic shock
Potential myocardial depression and acute metabolic acidosis
Vial P, Ferrés M, Vial C et al. Hantavirus in humans: a review of clinical aspects and management The Lancet Infectious Diseases, 2023; 23, e371-e382
This is different to the progression of HFRS, which typically has five phases:
Febrile Phase (3–7 Days)
Hypotensive Phase (Hours to 2 Days)
Oliguric Phase (3–7 Days)
Diuretic / Polyuric Phase (Days to Weeks)
Convalescent Phase (Weeks to 6 Months)
The initial febrile phase is still pretty non-specific in terms of presentation, but tends to include high fever, chills, intense headache, severe backache, and abdominal pain. Mortality rates vary by causative species, but range from 1 – 15%.
Vial P, Ferrés M, Vial C et al. Hantavirus in humans: a review of clinical aspects and management The Lancet Infectious Diseases, 2023; 23, e371-e382
Transmission control
Within the UK, Hantavirus infection caused by Andes virus is classified as a high consequence infectious disease (HCID). HCIDs are defined based on the following criteria:
Requires an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely
Acute infectious disease
Typically has a high case-fatality rate
May not have effective prophylaxis or treatment
Often difficult to recognise and detect rapidly
Ability to spread in the community and within healthcare settings
Interestingly, only the Andes Hantavirus is listed as a HCID, due to the risk of airborne human to human transmission. Once an HCID is confirmed or highly probable based on a combination of exposure history, symptoms, and diagnostic testing outcomes, the patient will be transferred by specialist transport teams to a designated HCID Treatment Center or High-Level Isolation Unit (HLIU). There are 7 adult and 5 paediatric Airborne HCID Treatment Centres in England, all of whom will hold specialist isolation facilities.
Early diagnosis of Hantavirus infection can be difficult, especially within the first 72 hours of symptoms, before the virus can be accurately detected in body secretions and excretions. Repeat diagnostic testing is often done 72 hours after symptom onset. As the initial presentation is fairly generic, it can take some time to realise what additional testing is required, and a good travel and activity history is key to informing diagnostic steps.
Within the UK, diagnostic testing options include:
Serology (Blood Tests): This is the primary diagnostic method. Laboratories use Enzyme-Linked Immunosorbent Assays (ELISA) or immunoblot assays to detect hantavirus-specific Immunoglobulin M (IgM) which looks for recent infection and IgG antibodies which looks for more established immune response, both by testing blood serum samples.
Molecular Testing (RT-PCR): Reverse transcription-polymerase chain reaction (RT-PCR) is used to detect hantavirus viral RNA in acute blood or blood samples during the viraemic phase, when the virus is present within the blood stream.
WHO update 6th May 2026
Internationally, one of the challenges for control in this specific outbreak, was that this wasn’t a point source exposure where everyone is incubating according to the same time frame, as people left the ship at different times, and were also isolating onboard the ship over different time periods based on the level of contact with the initially cases. This made initial components of contact tracing challenging, which then led to further possible exposures as some of the initial passengers returned to their home countries before the extent of the outbreak was understood.
Clinical management
There is no specific antiviral treatment option for Hantavirus so management focuses on supportive therapy, respiratory support (often in intensive care), fluid management, and for HFRS dialysis. Among patients who have severe respiratory symptoms as part of HCPS, the case fatality rate has been estimated to be approximately 38%.
As part of the follow up for this current outbreak, UK nationals, once repatriated have been taken to an isolation facility where they will be kept for up to 72 hours and initial clinical review and testing will be undertaken. As part of this clinical teams will then assess whether contacts who are not displaying symptoms can isolate at home or at another suitable location based on their living arrangements. Exposed individuals are generally being advised to self-isolate for up to 45 days from their last known exposure, but this self-isolation is voluntary. During the isolation period clinical networks will maintain daily contact to check for potential symptoms and undertake regular testing.
The World Health Organization (WHO) has recommended a 42-day quarantine period for the cruise passengers from their last exposure, although within the UK this has been extended to 45 days. Cases are managed, if symptoms develop using the following case definitions:
Confirmed Case: A patient with positive PCR testing for hantavirus in clinical samples, combined with travel on the MV Hondius from 1 April 2026 or contact with a passenger within 45 days of symptom onset.
Probable Case: A patient with compatible symptoms (e.g., fever, respiratory distress) and no other identified pathogen, linked by travel or close contact to the MV Hondius outbreak.
Possible/Suspected Case: A patient with compatible symptoms and no other identified pathogen, who had contact with a MV Hondius passenger within 45 days of symptom onset.
Previous outbreaks
Although all of this information seems rather intense and it is easy to see why the new media are trying to make a big story out of it, apart from those exposed we do need to put this outbreak into context. Outbreaks of Hantavirus happen with relative frequency, probably more than we know as diagnosis can be difficult identification may be underestimated, and some local outbreaks are probably under reported. To help demonstrate this I’ve put together a list of previous, easy to find, outbreaks along with their case numbers:
Argentina Regional Outbreak (Late 2025 – Early 2026)
Cases: A spike in localized regional cases with the NEJM reporting 34 cases from a single event.
Deaths: Up to 20 deaths.
Germany Voles-Linked Surge (2025)
Cases: 55 cases in the first half of the year (predominantly in Bavaria)
Driven by an ecological spike in the local bank vole population.
Brazil Farmland Outbreak (September 2022)
Cases: 22 cases.
Deaths: 10 deaths.
Traced to wood and rice mice exposure on agricultural properties.
Episodic Outbreaks in Los Santos, Panama (2022)
Cases: 29 cases recorded over nine months.
16 manifested as severe HCPS; no fatalities reported.
Argentina Andes Outbreak (2018)
Cases: 34 confirmed cases.
Deaths: 11 deaths.
Someone sick with ANDV attended a birthday party with 100 people; 5 people who were seated close to the individual later developed symptoms
Yosemite National Park, USA (2012)
Cases: 10 confirmed cases.
Deaths: 3 deaths.
Contracted by visitors staying in signature tent cabins infested with deer mice.
Chili (1997 – 1998)
Cases: 25 cases were officially recognized as part of the primary outbreak wave from July 1997 to January 1998.
When expanding the surveillance period from October 1995 through January 22, 1998, a total of 33 cases were confirmed nationwide
Epidemiologists verified human-to-human transmission across two out of three family clusters identified during the outbreak
The Korean War Epidemic (1950–1953)
Cases: 3,000+ UN soldiers infected.
The landmark historical event that first clinically defined Hantavirus Hemorrhagic Fever with Renal Syndrome (HFRS)
What is currently happening with this outbreak?
As this post has taken me a couple of weeks to pull together, I thought it was worth ending with the latest update I have available from the European Centre for Disease Prevention and Control (ECDC) on 24 May. At this point 12 cases have been reported in total, including 10 confirmed and 2 probable cases. One new case and no new deaths have been reported since the previous update (unclear when the last update was).
ECDC update on 24th May
The cruise ship M/V Hondius has had all passengers and crew disembarked and is currently docked in Rotterdam, the Netherlands, undergoing sanitation procedure.
The short answer is no, I don’t believe so and neither do many people who are far more expert than I that you will hear write and talk on this subject. This scenario has got me thinking though, if this outbreak hadn’t impacted European and US passengers whether we would have even heard about this outbreak at all. As you’ve seen in the outbreak section, Hantavirus outbreaks are not that uncommon. Was it because of passenger social media that it made headlines, because the cruise industry is big business, or because it impacted audiences because they saw passengers as being ‘like them’ and worrying that they too could be impacted on a holiday?
I think, whatever the reason, that this should be used as a wake up call for all of us to realise that infection diseases are global, and that we ignore infections that we don’t consider to impact ‘us’ at our risk. With global travel, with climate change, with changes in health surveillance due to certain US policies, the old way of looking at infectious diseases may not be fit for purpose. Too much of the world is in pandemic denial, and just doesn’t want to think about infection risk. We either experience coverage that induces panic, or ostriching where we don’t talk about it at all. Neither of these approaches are going to lead to the best outcomes or knowledge sharing in the face of a changing infection landscape. What needs to happen is for global networks to be built, for infrastructure to be invested in, and for communication to occur in a way that supports surveillance and knowledge acquisition. I don’t believe that Hantavirus is a risk for developing a new pandemic, but if we don’t take the time we have available to invest in planning, we won’t be as prepared for the next outbreak that could be.
Girlymicro 